This invention relates to a child-resistant blister pack for unit dosage forms. More particularly, but not exclusively, the blister pack is intended for containing and protecting solid unit dosage forms of the fast-dissolving type. These are particularly fragile and require to be packed in strong packaging to prevent them from being crushed during handling; but nevertheless the pack must be capable of being opened by an adult without damage to the dosage forms.
Many countries have introduced legislation in which standard tests are required to be complied with to render drug packs sufficiently difficult for children to open while still being openable relatively easily by an adult.
One form of known child-resistant blister pack is disclosed in U.S. Pat. No. 5,046,618 wherein the pack includes a blister film sheet having depressions therein in each of which there is a solid fast-dispersing dosage form. The blister film sheet is covered with a lidding sheet which overlies the depressions and which is secured to the blister film sheet so as to seal the unit dosage forms within the depressions. The material forming the blister pack is sufficiently strong such that even an adult has great difficulty in tearing it without weakening lines being provided in the pack.
In the blister pack of U.S. Pat. No. 5,046,618, the depressions are arranged in two parallel rows on either side of a central weakening line which extends longitudinally of the pack from an access region to a location which stops short of the opposite end of the pack. The weakening line is defined by a series of spaced perforations through the blister film sheet and the lidding sheet. A series of transverse weakening lines of a similar type are also provided in the blister pack between adjacent depressions in each row. The resultant network of weakening lines defines a plurality of individual dosage units, each of which includes one of the depressions containing a solid unit dosage form. Each dosage unit includes a peel region where part of the lidding sheet is not secured to the blister film. This peel region is disposed adjacent a respective one of the lines of weakness in the network so that it is exposed only when the blister pack has been torn along this line. Once the blister pack has been torn along this line, the peel region is exposed for manual grasping so as to enable the portion of the lidding sheet on the dosage unit to be peeled back to enable access to be gained to the unit dosage form within the depression. To enable access to be gained to the longitudinal weakening line, the line may extend to the adjacent end of the blister pack so as to provide an immediate access point. Alternatively, a further transverse line having its own access point may be provided in the blister pack. In the latter arrangement, the longitudinal weakening line extends to this further transverse line so that, when the pack is torn along the further transverse line, the access point for tearing the longitudinal weakening line is exposed.
U.S. Pat. No. 6,155,423 also discloses a blister pack which has child-resistant features and where a longitudinal weakening tear line and transverse weakening tear lines are provided in the blister pack so as to define individual dosage units containing the unit dosage forms. In this case, the ends of all the weakening tear lines terminate in regions at the edges of the blister pack which are more difficult to tear than weakening tear lines themselves and which are provided in the vicinity of indentations or notches extending inwardly towards the outer ends of the weakening tear lines to serve as intuitive indicators of a separation area for the user of the package.
While the blister packs described in the above mentioned publications are indeed child-resistant to a greater or lesser extent, there is a continuing requirement to make blister packs even more child resistant while still enabling relatively simple access by adults.
The present invention has for its object to provide an improved child-resistant blister pack.
According to the present invention, there is provided a child-resistant blister pack for unit dosage forms, said pack comprising:
(i) a blister film sheet with depressions therein;
(ii) unit dosage forms within the depressions;
(iii) a lidding sheet which overlies the depressions and which is secured to the film sheet so as to seal the unit dosage forms within the depressions; and
(iv) a network of lines of weakness in the pack defining a plurality of dosage units, each dosage unit including (a) one of said dosage forms sealed in one of the depressions and (b) a peel region where part of the lidding sheet is not secured to the blister film sheet, each peel region being disposed adjacent a respective one of the lines of weakness in the network;
wherein said lines of weakness include:
(1) a first line of weakness extending from a first access point so that, when the first access point is exposed, the blister film sheet and the lidding sheet can be torn along the first line of weakness to expose a second access point and also enable access to the peel region of the first dosage unit;
(2) a second line of weakness extending from the second access point so that, when the second access point is exposed, the blister film sheet and the lidding sheet can be torn along the second line of weakness to expose a third access point and also enable access to the peel region of the second dosage unit; and
(3) a third line of weakness which is spaced from the first line of weakness and which extends from the third access point so that, when the third access point is exposed, the blister film sheet and the lidding sheet can be torn along the third line of weakness to enable access to the peel region of a third dosage unit.
It will be appreciated that, in the blister pack of the present invention, tearing the pack along each weakening line only exposes one of the peel regions and the next access point for tearing along the next weakening line. This makes it much more difficult for the individual dosage units to be separated from the pack to the extent that their peel regions can be accessed. This is in contrast to the blister packs of U.S. Pat. Nos. 5,046,618 and 6,155,423 where, once access has been gained to the longitudinal weakening line, the whole of the pack can be torn into two separate parts making it easier to gain access to the individual dosage units in these separated parts. Additionally, in the present invention, since the user is forced to separate the individual dosage units from the remainder of the pack in a particular order, he or she will not be tempted initially tear the pack into two parts each containing a plurality of dosage units. Thus, the remaining dosage units in the blister pack are all kept together for safe and easy storage.
Preferably, the lines of weakness further include at least one additional line of weakness along which the blister film sheet and the lidding sheet are required to be torn in order to gain access to said first line of weakness. Where there is more than one such additional line of weakness, the arrangement is preferably such that these have to be torn in sequence in order to access said first line of weakness.
The pack may also include at least one further line of weakness with no access points and/or at least one visual feature giving the appearance of a line of weakness so as to act as a further child-resistant feature. An attempt to open the pack using these features would be unsuccessful and assist in causing the child to lose interest in opening the package.
In a preferred embodiment, said first line of weakness extends along two sides of said first dosage unit and along one side of said second dosage unit and terminates in a region which is aligned with and joined to said second line of weakness at said second access point. With such an arrangement, when said first dosage unit has been removed from the pack, the second access point is exposed, thus permitting the pack to be torn again along said second line of weakness to detach said second dosage unit from the pack. The first and second lines of weakness preferably terminate a short distance away from opposite sides of the pack. In this way, while it is impossible to gain entry to the respective lines of weakness by attempting to tear into the opposite sides of the pack, it is possible to tear the dosage units completely from the pack once they have been torn along their respective lines of weakness because the tear in the material has already been started.
In a preferred embodiment, the first line of weakness includes inclined portions which are preferably mutually perpendicular and which may be linear. The first line of weakness may comprise the mutually inclined portions with an intermediate connecting portion between them. This promotes tearing of the pack along the desired line rather than continuing along a straight line. It also obviates the risk of unwanted continued tearing along said third line of weakness even when the latter is in alignment with the first line of weakness.
The intermediate connecting portion may be inclined with respect to both of the inclined portions and may be linear.
In most cases, the blister pack includes more than three blisters and dosage forms. In which case, further lines of weakness similar to said first, second and third lines of weakness may be provided as required to provide a network of lines arranged so that the further dosage units have to be removed in a predetermined order.
It is within the scope of the present invention to provide a pack where further lines of weakness define at least one unit without a unit dosage form therein. Such a unit may be provided at a location where it must be torn away before access can be gained to any of the dosage forms.
For the avoidance of doubt, it is hereby stated that references to xe2x80x9cfirstxe2x80x9d, xe2x80x9csecondxe2x80x9d and xe2x80x9cthirdxe2x80x9d in relation to the dosage units are included solely for assisting in distinguishing between individual dosage units in the pack and are not to be taken as indicating that these are the first, second and third dosage units to be accessed when the pack is opened. The same applies to the use of xe2x80x9cfirstxe2x80x9d, xe2x80x9csecondxe2x80x9d and xe2x80x9cthirdxe2x80x9d in relation to the weakening lines and the access points. This will become apparent from the description hereinafter in relation to the embodiment of FIG. 5.